Paravalvular leak resistant prosthetic heart valve system

ABSTRACT

A paravalvular leak resistant prosthetic heart valve system including a stent frame, a valve structure and a sealing mechanism. The stent frame has a surface. The valve structure is associated with the stent frame. The sealing mechanism at least partially extends over the surface of the stent frame. The sealing mechanism includes at least one semi-permeable membrane and an osmotic gradient driving material.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Division of U.S. patent application Ser. No.14/259,340, filed Apr. 23, 2014, entitled “Paravalvular Leak ResistantProsthetic Heart Valve System”, the entire teachings of which areincorporated herein by reference.

BACKGROUND

The present disclosure relates to systems and methods of reducingleakage around a medical implant. More particularly, the inventionrelates to a paravalvular leak resistant prosthetic heart valve system.

A human heart includes four heart valves that determine the pathway ofblood flow through the heart: the mitral valve, the tricuspid valve, theaortic valve, and the pulmonary valve. The mitral and tricuspid valvesare atrioventricular valves, which are between the atria and theventricles, while the aortic and pulmonary valves are semilunar valves,which are in the arteries leaving the heart. Ideally, native leaflets ofa heart valve move apart from each other when the valve is in an openposition, and meet or “coapt” when the valve is in a closed position.Problems that may develop with valves include stenosis in which a valvedoes not open properly, and/or insufficiency or regurgitation in which avalve does not close properly. Stenosis and insufficiency may occurconcomitantly in the same valve. The effects of valvular dysfunctionvary, with regurgitation or backflow typically having relatively severephysiological consequences to the patient.

Diseased or otherwise deficient heart valves can be repaired or replacedwith an implanted prosthetic heart valve. Conventionally, heart valvereplacement surgery is an open heart procedure conducted under generalanesthesia, during which the heart is stopped and blood flow iscontrolled by a heart-lung bypass machine.

Traditional open heart surgery inflicts significant patient trauma anddiscomfort, and exposes the patient to a number of potential risks, suchas infection, stroke, renal failure, and adverse effects associated withthe use of the heart-lung bypass machine, for example.

Due to the drawbacks of open-heart surgical procedures, there has beenan increased interest in minimally invasive replacement of cardiacvalves. Recently, prosthetic valves supported by stent frame structuresthat can be delivered percutaneously using a catheter-based deliverysystem have been developed for heart and venous valve replacement. Withthese percutaneous transcatheter (or transluminal) techniques, a valveprosthesis is compacted for delivery via a catheter and then advanced,for example, through an opening in the femoral artery and through thedescending aorta to the heart, where the prosthesis is then deployed inthe annulus of the valve to be repaired (e.g., the aortic valveannulus).

Percutaneously delivered prosthetic valves may include eitherself-expandable, balloon-expandable, and/or mechanically-expandablestent frame structures with a valve structure attached or coupled to theinterior of the stent frame structure. The prosthetic valve may bereduced in diameter, by crimping onto a balloon catheter or by beingcontained within a sheath component of a delivery catheter, and advancedthrough the venous or arterial vasculature.

Once the prosthetic valve is positioned at the treatment site, forinstance within an incompetent native valve, the stent frame structuremay be expanded to hold the prosthetic valve firmly in place. Oneexample of a stented prosthetic valve is disclosed in U.S. Pat. No.5,957,949 to Leonhardt et al., which is incorporated by reference hereinin its entirety.

Although transcatheter techniques have attained widespread acceptancewith respect to the delivery of conventional stents to restore vesselpatency, only mixed results have been realized with percutaneousdelivery of a relatively more complex prosthetic heart valve.

Various types and configurations of prosthetic heart valves areavailable, and continue to be refined. The actual shape andconfiguration of any particular prosthetic heart valve is dependent tosome extent upon native shape and size of the valve being repaired(i.e., mitral valve, tricuspid valve, aortic valve, or pulmonary valve).In general, prosthetic heart valve designs attempt to replicate thefunctions of the valve being replaced and thus may include a valvestructure comprising one or more leaflet-like structures.

With a bioprosthesis construction, the replacement valve may include avalved vein segment that is mounted in some manner within an expandablestent frame to make a valved stent (or “stented prosthetic heartvalve”). For many percutaneous delivery and implantation systems, theself-expanding valved stent is crimped down to a desired size and heldin that compressed state within an outer sheath, for example. Retractingthe sheath from the valved stent allows the stent to self-expand to alarger diameter, such as when the valved stent is in a desired positionwithin a patient.

In other percutaneous implantation systems, the valved stent can beinitially provided in an expanded or uncrimped condition, thencompressed or crimped on a balloon portion of a catheter until it is asclose to the diameter of the catheter as possible. Once delivered to theimplantation site, the balloon is inflated to deploy the so-configuredprosthesis. With either of these types of percutaneous stent deliverysystems, conventional sewing of the prosthetic heart valve to thepatient's native tissue is typically not necessary.

It is imperative that the stented prosthetic heart valve be accuratelypositioned relative to the native valve immediately prior to deploymentfrom the catheter as successful implantation requires the transcatheterprosthetic heart valve intimately lodge and seal against the nativetissue. If the prosthesis is incorrectly positioned relative to thenative tissue, serious complications can result as the deployed devicecan leak and may even dislodge from the implantation site.

Even when the stented prosthetic heart valve is accurately positioned inthe native valve, at least a portion of the annulus may have anirregular shape, which impacts the ability to form a good seal betweenthe stented prosthetic heart valve and the native valve.

Leaking of blood around an implanted prosthetic heart valve is referredto as a paravalvular leak, which can lead to heart failure and increaserisk of infectious endocarditis.

In light of the above, although there have been advances in percutaneousvalve replacement techniques and devices, there is a continued desire toprovide enhanced sealing between the prosthetic heart valve and thenative valve.

SUMMARY

An embodiment of the invention is directed to a paravalvular leakresistant prosthetic heart valve system that includes a stent, a valvestructure and a sealing mechanism. The stent frame has a surface. Thevalve structure is associated with the stent frame. The sealingmechanism at least partially extends over the surface of the stentframe. The sealing mechanism includes at least one semi-permeablemembrane and at least one osmotic gradient driving material.

Another embodiment of the invention is directed to a method of reducingparavalvular leakage from a prosthetic heart valve. A prosthetic heartvalve is provided that includes a stent frame having a surface, a valvestructure associated with the stent frame, a sealing mechanismcomprising at least one semi-permeable membrane and at least one osmoticmaterial driving compound. The sealing mechanism is positioned at leastpartially over the surface of the stent frame. The prosthetic heartvalve is deployed in a patient. The osmotic gradient driving materialcauses fluid of the patient to pass through the at least onesemi-permeable membrane. The fluid that passes through the at least onesemi-permeable membrane causes the sealing mechanism to swell and suchswelling reduces paravalvular leakage between the prosthetic heart valveand tissue of the patient.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1a is a side view of paravalvular leakage resistant prostheticheart valve according to an embodiment of the invention.

FIG. 1b is a side view of paravalvular leakage resistant prostheticheart valve according to an embodiment of the invention.

FIG. 2 is a bottom view of the paravalvular leakage resistant prostheticheart valve of FIG. 1 b.

FIG. 3 is a sectional view of the paravalvular leakage resistantprosthetic heart valve.

FIG. 4 is a sectional view of an alternative embodiment of theparavalvular leakage resistant prosthetic heart valve.

FIG. 5 is a side view of the paravalvular leakage resistant prostheticheart valve in a loaded configuration associated with a delivery system.

FIG. 6 is a side view of the paravalvular leakage resistant prostheticheart valve in an expanded configuration with respect to a nativeannulus.

FIG. 7 is a side view of the paravalvular leakage resistant prostheticheart valve with the sealing mechanism in a swollen configuration toenhance a seal between the prosthetic heart valve and the nativeannulus.

DETAILED DESCRIPTION

Specific embodiments of the present invention are now described withreference to the figures, wherein like reference numbers indicateidentical or functionally similar elements. The terms “distal” and“proximal” are used in the following description with respect to aposition or direction relative to the treating clinician. “Distal” or“distally” are a position distant from or in a direction away from theclinician. “Proximal” and “proximally” are a position near or in adirection toward the clinician. As used herein with reference to animplanted valve prosthesis, the terms “distal,” “outlet” and “outflow”are understood to mean downstream to the direction of blood flow, andthe terms “proximal,” “inlet” or “inflow” are understood to meanupstream to the direction of blood flow. In addition, as used herein,the terms “outward” or “outwardly” refer to a position radially awayfrom a longitudinal axis of a frame of the valve prosthesis and theterms “inward” or “inwardly” refer to a position radially toward alongitudinal axis of the frame of the valve prosthesis. As well theterms “backward” or “backwardly” refer to the relative transition from adownstream position to an upstream position and the terms “forward” or“forwardly” refer to the relative transition from an upstream positionto a downstream position.

The invention is directed to a system and method for sealing aprosthetic heart valve or other implanted tissue with respect to anative valve in which the prosthetic heart valve is placed. Theinvention thereby reduces the potential of a paravalvular leak and theassociated complications resulting therefrom.

The system 10 includes a prosthetic heart valve 20 and an associatedsealing mechanism 30, as illustrated in the figures. In general terms,the prosthetic heart valves 20 of the present disclosure include a valvestructure (tissue or synthetic) 24 mounted with respect to a stent orstent frame 22, as illustrated in FIGS. 1a, 1b and 2.

The valve structure 24 is drawn generally in FIG. 1a and the valvestructure 24 is omitted from FIG. 1b to enhance understanding of theother aspects of the invention because as referred to herein, theprosthetic heart valve 20 as used in accordance with the various devicesand methods may include a wide variety of different configurations, suchas a bioprosthetic heart valve structure having one or more tissueleaflets or a synthetic heart valve structure having one or morepolymeric, metallic, or tissue-engineered leaflets, and can bespecifically configured for replacing any heart valve.

In accordance with embodiments hereof, one or more portions of the valvestructure, body, component, or member, and valve leaflets thereof, canbe formed, for example, from one or more biocompatible syntheticmaterials, synthetic polymers, autograft tissue, homograft tissue,xenograft tissue, or one or more other suitable materials. In someembodiments, one or more portions of the valve structure and valveleaflets thereof can be formed, for example, from bovine, porcine,equine, ovine, and/or other suitable animal tissues. In accordance withembodiments hereof, one or more portions of the valve structure andvalve leaflets thereof may be made of or formed from a natural materialobtained from, for example, heart valves, aortic roots, aortic walls,aortic leaflets, pericardial tissue, such as pericardial patches, bypassgrafts, blood vessels, intestinal submucosal tissue, umbilical tissueand the like from humans or animals. In accordance with otherembodiments hereof, synthetic materials suitable for use as valvestructure components and valve leaflets thereof include DACRON®polyester commercially available from Invista North America S.A.R.L. ofWilmington, Del., other cloth materials, nylon blends, polymericmaterials, and vacuum deposition nitinol fabricated materials. In anembodiment, one or more portions of the valve structure and valveleaflets thereof can be made of an ultra-high molecular weightpolyethylene material commercially available under the trade designationDYNEEMA from Royal DSM of the Netherlands. With certain leafletmaterials, it may be desirable to coat one or both sides of the leafletwith a material that will prevent or minimize overgrowth. It is furtherdesirable that the leaflet material is durable and not subject tostretching, deforming, or fatigue. In accordance with other embodimentshereof, the valve structure can comprise one or more valve leaflets. Forexample, the valve structure can be in the form of a tri-leaflet valve,a bi-leaflet valve, a quad-leaflet valve or another suitable valve. Inaccordance with other embodiments hereof, the valve structure cancomprise two or three leaflets that are fastened together at enlargedlateral end regions to form commissural joints, with the unattachededges forming coaptation edges of the valve structure. In accordancewith other embodiments hereof, the prosthetic valve leaflets can befastened to a skirt of a graft material, which in turn can be attachedor coupled to the stent frame.

As referred to herein, the prosthetic heart valve 20 as used inaccordance with the devices and methods of the present disclosure can begenerally used for replacement of a native aortic, mitral, pulmonic ortricuspid valve. The prosthetic heart valve 20 can also be used as avenous valve, or to replace a failed bioprosthesis, such as in the areaof an aortic, mitral, pulmonic or tricuspid valve.

The stent frame 22 is positionable in an expanded arrangement (FIGS. 1aand 1b ) for maintaining the prosthetic heart valve 20 in a desiredlocation such as with respect to the native valve. The stent ispositionable in a collapsed configuration for loading within thedelivery system as illustrated in FIG. 5.

FIG. 1a is a front or side view of a prosthetic heart valve 20 inaccordance with an embodiment hereof. The prosthetic heart valve 20includes a valve structure 24 supported within a stent frame 22. Stentframe 22 may include an inlet portion 25, an hourglass-shaped central orvalve-retaining tubular portion 26, an outlet portion 27, support arms28, and a sealing mechanism 30. Support arms 28 may be configured tocapture leaflets during delivery of the prosthetic heart valve 20.Central portion 26 may be configured to pinch a muscular ridge of thenative annulus when implanted therein. The reduced-waist region of thehourglass shape or profile of stent frame 22 may be located on ordefined within central portion 26 around the entire circumference ofstent frame 22. Stent frame 22 may also provide axial fixation bycreating tensioning of the chordae tendinae. Sealing mechanism 30 may bepositioned over at least a portion of the outer surface of stent frame22.

FIG. 1b is a front or side view of a prosthetic heart valve 20 inaccordance with an embodiment hereof. The prosthetic heart valve 20includes a valve structure supported within a stent frame 22 and asealing mechanism 30 positioned over at least a portion of the outersurface of stent frame 22.

In certain embodiments, the stent frame 22 is constructed to self-deployor self-expand when released from the delivery system. For example, thestented prosthetic heart valve useful with the present disclosure can bea prosthetic valve sold under the trade name CoreValve® available fromMedtronic, Inc. Other non-limiting examples of transcatheter heart valveprostheses useful with systems and methods of the present disclosure aredescribed in U.S. Pat. No. 8,052,750; U.S. Patent Publication Nos.2006/0265056; 2007/0239266; and 2007/0239269, and U.S. patentapplication Ser. No. 14/175,100, the teachings of each of which areincorporated herein by reference.

Some embodiments of the stent frames 22 can be a series of wires, wiresegments and/or struts arranged such that they are capable ofself-transitioning from a collapsed arrangement to a radially expandedarrangement. In constructions, one or more portions of the stent framesupport structure 22 can be formed of one or more metals and/or othermaterials.

The wires and/or struts may be arranged in such a way that the stentframe support structure allows for folding or compressing or crimping toa compressed or compacted arrangement in which its internal diameter issmaller than its internal diameter when in the expanded arrangement. Insome embodiments, the valve prosthesis comprising a stent frame supportstructure with an attached or coupled valve structure can be mounted ina collapsed or compressed configuration or arrangement into or onto adelivery system.

In some embodiments, the stent frame 22 can be capable ofself-transitioning from the collapsed configuration to the radiallyexpanded configuration. The material from which the stent frame 22 isfabricated can permit the stent frame 22 to be compressed andre-expanded multiple times without damaging the structure of the stentframe 22.

The wires of the stent frame support structure 22 in embodiments of thepresent disclosure can be formed from a shape memory material such as anickel titanium alloy (e.g., Nitinol™). With this material, the stentframe support structure 22 is self-expandable from the compressedarrangement to the expanded arrangement, such as by the removal ofexternal forces (e.g., compressive forces) or by the application ofheat, energy, and the like.

As an alternative to fabricating the stent frame 22 from a plurality ofwires, the stent frame 22 may be laser-cut from a single piece ofmaterial. In other embodiments, the valve structure 24 and the stentframe 22 can be fabricated at the same time, such as may be accomplishedusing high-strength nano-manufactured NiTi films produced at AdvanceBioProsthetic Surfaces (ABPS).

To transform between a compressed arrangement and a deployedarrangement, the stent frame support structure in accordance withembodiments described herein may be formed from a self-expandingmaterial that has a mechanical memory to return to the deployedconfiguration. Accordingly in accordance with embodiments hereof, stentframes may be made from stainless steel, a pseudo-elastic metal such asa nickel titanium alloy or nitinol, or a so-called super alloy, whichmay have a base metal of nickel, cobalt, chromium, or other metal.Mechanical memory may be imparted to a tubular structure that may formstent frames by thermal treatment to achieve a spring temper instainless steel, for example, or to set a shape memory in a susceptiblemetal alloy, such as nitinol, or a polymer, such as any of the polymersdisclosed in U.S. Patent Publication No. 2004/0111111, which isincorporated by reference herein in its entirety. In accordance withother embodiments hereof, a stent frame of the valve prosthesis can beformed entirely or in part by a biocompatible or biodegradable material.In accordance with other embodiments hereof, one or more portions of astent frame of the valve prosthesis may be self-expandable, balloonexpandable, and/or mechanically-expandable.

One or more valve prosthesis embodiments disclosed herein may comprise asingle support arm, a plurality of support arms, support arms with innerand outer support arm members, variations of structures thereof, and/orone more pairs of support arms having various structures and attachmentpoints for providing various functions when implanted. It should beunderstood that the illustrated embodiments hereof are not limited tothe number or configuration of support arms illustrated in each figureand that one or more support arms, one or more pairs of support armsand/or the various structures therefore may be substituted across thevarious embodiments disclosed herein without departing from the scopehereof.

In one or more embodiments, valve prosthesis may comprise one or moresupport arms for engaging one or more native valve leaflets. In one ormore embodiments, valve prosthesis may comprise one or more support armsfor engaging one or more native chordae. In one or more embodiments,valve prosthesis may comprise one or more support arms for engaging oneor more native valve commissures. In one or more embodiments, valveprosthesis may comprise one or more support arms for engaging a nativevalve annulus. In one or more embodiments, valve prosthesis may compriseone or more support arms for engaging one or more native valve tissuesor structures. For example, one or more support arms may engage orinteract with valve leaflets, chordae, commissures and/or annulus. Inone or more embodiments, valve prosthesis may comprise one or moresupport arms for engaging one or more heart tissues or structures. Inone or more embodiments, valve prosthesis may comprise one or moresupport arms for engaging the pulmonary artery. In one or moreembodiments, valve prosthesis may comprise one or more support arms forengaging the aorta.

In one or more embodiments, one or more support arms may be coupled orconnected to a central portion, an inflow portion and/or an outflowportion of valve prosthesis. In one or more embodiments, valveprosthesis may comprise one or more support arms that may apply one ormore forces such as a radial force, an axial force, a lateral force, aninward force, an outward force, an upstream force, and/or a downstreamforce to one or more valve structures, valve tissues, heart structuresand/or heart tissues. In some embodiments, one or more support arms, asdescribed herein, may be considerably longer, shorter, wider, ornarrower than shown. In some embodiments, one or more support arms, asdescribed herein, may be narrower at the base, bottom or proximal endportion where the support arms couple to the inflow portion, centralportion and/or the outflow portion of the valve prosthesis and wider atthe top or distal end portion of the support arm. In some embodiments,one or more support arms, as described herein, may be wider at the base,bottom, or proximal end portion where the support arms couple to theinflow portion, central portion and/or the outflow portion of the valveprosthesis and narrower at the top or distal end portion of the supportarm. In some embodiments, one or more support arms, as described herein,may be configured to be a shape and size that can provide a positioningfunction, valve leaflet capturing function, a stabilization function, ananti-migration function, and/or an anchoring function for valveprosthesis in accordance herewith when the prosthesis is deployed at anative valve site. In some embodiments, one or more support arms, asdescribed herein, may interact, engage, capture, clamp, push against oneor more native tissues or structures such as valve leaflets, chordae,annulus, ventricle, and/or atrium. In some embodiments, one or moresupport arms, as described herein, may comprise a first portion thatextends in a forward direction and a second portion that extends in abackward direction. In some embodiments, one or more support arms, asdescribed herein, may comprise a first portion that extends in abackward direction and a second portion that extends in a forwarddirection. In some embodiments, one or more support arms, as describedherein, may comprise one or more portions that may extend horizontally,longitudinally, axially, circumferentially, inward, outward, forward,and/or backward. In some embodiments, one or more support arms, asdescribed herein, may comprise more than one configuration. For example,one or more embodiments of one or more support arms, as describedherein, may extend in first direction in a delivery, compressed, and/orcollapsed configuration and in a second direction in a deployed orexpanded configuration. In one example, a first or delivery directionmay be a forward direction and a second or deployed direction may be abackward direction. In another example, a first or delivery directionmay be a backward direction and a second or deployed direction may be aforward direction. In one or more embodiments, one or more support arms,as described herein, may comprise a first shape in a deliveryconfiguration and a second shape in a deployed configuration. Forexample, a first or delivery shape may be a straight shape and a secondor deployed shape may be a curved shape.

In some embodiments, one or more support arms, as described herein, maycomprise one or more portions that comprise one or more spiral shapes,S-shapes, C-shapes, U-shapes, V-shapes, loop shapes, tine shapes, and/orprong shapes. In some embodiments, one or more support arms, asdescribed herein, may comprise a curved, rounded, and/or flared distalend portion. In some embodiments, one or more support arms, as describedherein, may be connected, coupled, attached, and/or extend from one ormore locations positioned on the inflow portion, the central portionand/or the outflow portion of the valve prosthesis. For example, in someembodiments, one or more support arms, as described herein, may beconnected, coupled, attached, and/or extend from one or more locationspositioned on the inflow portion, the central portion and/or the outflowportion of the valve prosthesis stent frame support structure. In someembodiments, one or more support arms, as described herein, may compriseat least a portion that may comprise at least one free end not attachedor coupled to the stent frame of the valve prosthesis. In one or moreembodiments, one or more support arms and/or one or more of componentsof a support arm may comprise one or more fixation elements or memberssuch as anchors, barbs, prongs, clips, grommets, sutures, and/or screws.In one or more embodiments, one or more support arms and/or one or moreof components of a support arm may comprise, for example, one or moreactive and/or passive fixation elements or members.

In one or more embodiments, valve prosthesis may comprise an inflowportion, a central portion, and an outflow portion. In one or moreembodiments, the valve prosthesis may comprise a single unitarystructure or the valve prosthesis may comprise one or more components orportions coupled or connected together. In one or more embodiments, thevalve prosthesis may comprise a central portion comprising a valve body,member, or component. In one or more embodiments, the valve body,structure, member, or component may comprise one or more valve leaflets.In one or more embodiments in accordance herewith, the valve leaflets ofthe valve body, structure, member, or component are attached to anupstream end of the central portion to extend into an inflow portion ofthe frame, such that the valve body, structure, member, or component isnot solely located on or within the outflow portion of the frame. In oneor more embodiments, valve member and/or one or more of its componentsmay comprise one or more materials, as described herein.

In one or more embodiments, the central portion of valve prosthesisand/or one or more of its components may comprise one or morelongitudinal or cross-sectional shapes, such as a geometric shape, anon-geometric shape, a tubular shape, a cylindrical shape, a circularshape, an elliptical shape, an oval shape, a triangular shape, arectangular shape, a hexagonal shape, a square shape, an hourglassshape, a polygonal shape, a funnel shape, a nozzle shape, a D-shape, asaddle shape, a planar shape, a non-planar shape, a simple geometricshape, and/or a complex geometric shape. In one or more embodiments, thecentral portion and/or one or more of its components may comprise one ormore fixation elements or members such as anchors, barbs, clips, prongs,grommets, sutures, and/or screws. In one or more embodiments, thecentral portion and/or one or more of its components may comprise aframe, a framework, or stent-like structure, as described herein. In oneor more embodiments, the outflow portion and/or one or more of itscomponents may comprise, be covered with, be coated with, or be attachedor coupled to one or more materials, as described herein. In one or moreembodiments, the central portion and/or one or more of its componentsmay comprise one or more support arms, components, or members asdescribed herein. In one or more embodiments, one or more support armsmay comprise one or more cantilever components or portions. In one ormore embodiments, the central portion and/or one or more of itscomponents, such as one or more support arms, may be designed to engageand/or push against the native valve annulus. In one or moreembodiments, the central portion and/or one or more of its components,such as one or more support arms, may be designed to engage, capture,clamp, hold, and/or trap one or more native valve leaflets. In one ormore embodiments, the central portion and/or one or more of itscomponents, such as one or more support arms, may be designed to engage,capture, clamp, hold, and/or trap one or more native chordae. In one ormore embodiments, one or more support arms may create or exert a tensionforce to native chordae. In one or more embodiments, the central portionand/or one or more of its components, such as one or more support arms,may be designed to engage and/or push against one or more native valvecommissures.

In one or more embodiments, valve prosthesis may comprise an inflow,inlet, upstream, or proximal portion connected, coupled, positioned,and/or located at a proximal end or proximal end portion of the centralportion of the valve prosthesis. In one or more embodiments, the inflowportion and/or one or more of its components may contact, engage,fixate, capture, clamp, pierce, hold, position, and/or seal the valveprosthesis to one or more heart structures and/or tissues such as atrialtissue, ventricle tissue, valve tissue, annulus tissue, the floor of anatrium, and/or the floor of a ventricle. For example, the inflow portionand/or one or more of its components may engage atrial tissue if thevalve prosthesis is positioned in a native mitral valve whereas theinflow portion and/or one or more of its components may engage ventricletissue if the valve prosthesis is positioned in a native aortic valve.In one or more embodiments, the inflow portion and/or one or more of itscomponents may exert one or more forces, for example, radial and/oraxial forces, to one or more heart structures and/or heart tissues. Inone or more embodiments, the inflow portion and/or one or more of itscomponents may comprise one or more fixation elements or members such asanchors, barbs, clips, prongs, grommets, sutures, and/or screws. In oneor more embodiments, the inflow portion and/or one or more of itscomponents may comprise one or more longitudinal or cross-sectionalshapes, such as a geometric shape, a non-geometric shape, a tubularshape, a cylindrical shape, a circular shape, an elliptical shape, anoval shape, a triangular shape, a rectangular shape, a hexagonal shape,a square shape, a polygonal shape, a funnel shape, a nozzle shape, aD-shape, an S-shape, a saddle shape, a simple geometric shape, and/or acomplex geometric shape. In one or more embodiments, the inflow portionand/or one or more of its components may be designed to deform to theshape of the native anatomy when the valve prosthesis is implanted. Forexample, the inflow portion may deform from a pre-delivery circularshape to a post-delivery D-shape following the delivery of the valveprosthesis to a native mitral valve. In one or more embodiments, theinflow portion and/or one or more of its components may comprise aframe, a framework, or stent-like structure, as described herein. In oneor more embodiments, the inflow portion and/or one or more of itscomponents may comprise, be covered with, be coated with, or be attachedor coupled to one or more materials, as described herein. In one or moreembodiments, the inflow portion and/or one or more of its components maycomprise one or more support arms, components, or members as describedherein. In one or more embodiments, one or more support arms maycomprise one or more cantilever components or portions. In one or moreembodiments, the inflow portion and/or one or more of its components,such as one or more support arms, may be designed to engage and/or pushagainst the native valve annulus. In one or more embodiments, the inflowportion and/or one or more of its components, such as one or moresupport arms, may be designed to engage, capture, clamp, hold, and/ortrap one or more native valve leaflets. In one or more embodiments, theinflow portion and/or one or more of its components, such as one or moresupport arms, may be designed to engage, capture, clamp, hold, and/ortrap one or more native chordae. In one or more embodiments, one or moresupport arms may create or exert a tension force to native chordae. Inone or more embodiments, the inflow portion and/or one or more of itscomponents, such as one or more support arms, may be designed to engageand/or push against one or more native valve commissures.

In one or more embodiments, valve prosthesis may comprise an outflow,outlet, downstream, or distal portion connected, coupled, positioned,and/or located at a distal end or distal end portion of the centralportion of the valve prosthesis. In one or more embodiments, the outflowportion and/or one or more of its components may contact, engage,fixate, capture, clamp, pierce, hold, position, and/or seal the valveprosthesis to one or more heart structures and/or tissues such as atrialtissue, ventricle tissue, valve tissue, valve leaflet tissue, annulustissue, and/or chordae tissue. For example, the outflow portion and/orone or more of its components may engage leaflet tissue, chordae tissue,and/or ventricle tissue if the valve prosthesis is positioned in anative mitral valve whereas the outflow portion and/or one or more ofits components may engage leaflet tissue and/or aortic tissue if thevalve prosthesis is positioned in a native aortic valve. In one or moreembodiments, the outflow portion and/or one or more of its componentsmay exert one or more forces, for example, radial and/or axial forces,to one or more heart structures and/or heart tissues. In one or moreembodiments, the outflow portion and/or one or more of its componentsmay comprise one or more fixation elements or members such as anchors,barbs, prongs, clips, grommets, sutures, and/or screws. In one or moreembodiments, the outflow portion and/or one or more of its componentsmay comprise one or more longitudinal or cross-sectional shapes, such asa geometric shape, a non-geometric shape, a tubular shape, a cylindricalshape, a circular shape, an elliptical shape, an oval shape, atriangular shape, a rectangular shape, a hexagonal shape, a squareshape, a polygonal shape, a funnel shape, a nozzle shape, a D-shape, anS-shape, a saddle shape, a simple geometric shape, and/or a complexgeometric shape. In one or more embodiments, the outflow portion and/orone or more of its components may be designed to deform to the shape ofthe native anatomy when the valve prosthesis is implanted. For example,the outflow portion may deform from a pre-delivery circular shape to apost-delivery D-shape following the delivery of the valve prosthesis toa native mitral valve. In one or more embodiments, the outflow portionand/or one or more of its components may comprise a frame, a framework,or stent-like structure, as described herein. In one or moreembodiments, the outflow portion and/or one or more of its componentsmay comprise, be covered with, be coated with, or be attached or coupledto one or more materials, as described herein. In one or moreembodiments, the outflow portion and/or one or more of its componentsmay comprise one or more support arms, components, or members asdescribed herein. In one or more embodiments, the outflow portion and/orone or more of its components, such as one or more support arms, may bedesigned to engage, capture, clamp, hold, and/or trap one or more nativevalve leaflets. In one or more embodiments, the outflow portion and/orone or more of its components, such as one or more support arms, may bedesigned to engage, capture, clamp, hold, and/or trap one or more nativechordae. In one or more embodiments, one or more support arms may createor exert a tension force to native chordae. In one or more embodiments,the outflow portion and/or one or more of its components, such as one ormore support arms, may be designed to engage and/or push against one ormore native valve commissures. In one or more embodiments, the outflowportion and/or one or more of its components, such as one or moresupport arms, may be designed to engage and/or push against the nativevalve annulus. In one or more embodiments, one or more support arms maycomprise one or more cantilever components or portions.

In one or more embodiments, valve prosthesis and/or one or more of itscomponents or portions may comprise, be covered with, be coated with, orbe attached or coupled to one or more biocompatible materials orbiomaterials, for example, titanium, titanium alloys, Nitinol, TiNialloys, shape memory alloys, super elastic alloys, aluminum oxide,platinum, platinum alloys, stainless steels, stainless steel alloys,MP35N, elgiloy, haynes 25, stellite, pyrolytic carbon, silver carbon,glassy carbon, polymers or plastics such as polyamides, polycarbonates,polyethers, polyesters, polyolefins including polyethylenes orpolypropylenes, polystyrenes, polyurethanes, polyvinylchlorides,polyvinylpyrrolidones, silicone elastomers, fluoropolymers,polyacrylates, polyisoprenes, polytetrafluoroethylenes, polyethyleneterephthalates, fabrics such as woven fabrics, nonwoven fabrics, porousfabrics, semi-porous fabrics, nonporous fabrics, Dacron fabrics,polytetrafluoroethylene (PTFE) fabrics, polyethylene terephthalate (PET)fabrics, materials that promote tissue ingrowth, rubber, minerals,ceramics, hydroxapatite, epoxies, human or animal protein or tissue suchas collagen, laminin, elastin or fibrin, organic materials such ascellulose, or compressed carbon, and/or other materials such as glass,and the like. Materials that are not considered biocompatible may bemodified to become biocompatible by a number of methods well known inthe art. For example, coating a material with a biocompatible coatingmay enhance the biocompatibility of that material. Biocompatiblematerials or biomaterials are usually designed and constructed to beplaced in or onto tissue of a patient's body or to contact fluid of apatient's body. Ideally, a biocompatible material or biomaterial willnot induce undesirable reactions in the body such as blood clotting,tumor formation, allergic reaction, foreign body reaction (rejection) orinflammatory reaction; will have the physical properties such asstrength, elasticity, permeability, and flexibility required to functionfor the intended purpose; may be purified, fabricated and sterilizedeasily; will substantially maintain its physical properties and functionduring the time that it remains in contact with tissues or fluids of thebody.

In one or more embodiments, valve prosthesis and/or one or more of itscomponents or portions may comprise and/or be coupled or attached to oneor more graft materials. In accordance with embodiments hereof, thegraft material or portions thereof may be a low-porosity woven fabric,such as polyester, DACRON® polyester, or polytetrafluoroethylene (PTFE),which creates a one-way fluid passage when attached to the stent frameof the valve prosthesis. In an embodiment, the graft material orportions thereof may be a looser knit or woven fabric, such as apolyester or PTFE knit, which can be utilized when it is desired toprovide a medium for tissue ingrowth and the ability for the fabric tostretch to conform to a curved surface. In another embodiment, polyestervelour fabrics may alternatively be used for the graft material orportions thereof, such as when it is desired to provide a medium fortissue ingrowth on one side and a smooth surface on the other side.These and other appropriate cardiovascular fabrics are commerciallyavailable from Bard Peripheral Vascular, Inc. of Tempe, Ariz., forexample. In another embodiment, the graft material or portions thereofmay be a natural material, such as pericardium or another membranoustissue.

In one or more embodiments, valve prosthesis and/or one or more of itscomponents or portions may comprise, be coated with, be covered with, beconstrained by, or be attached or coupled to a shape memory material, abioresorbable material, and/or a biodegradable material, such as anatural or synthetic biodegradable polymer, non-limiting examples ofwhich include polysaccharides such as alginate, dextran, cellulose,collagen, and chemical derivatives thereof, proteins such as albumin,and copolymer blends thereof, alone or in combination with syntheticpolymers, polyhydroxy acids, such as polylactides, polyglycolides andcopolymers thereof, poly(ethylene terephthalate), poly(hydroxybutyricacid); poly(hydroxyvaleric acid), poly [lactide-co-(E-caprolactone)];poly[glycolide-co-(E-caprolactone)], polycarbonates, poly(pseudo aminoacids); poly(amino acids); poly(hydroxyalkanoate)s, polyanhydrides;polyortho esters, and blends and copolymers thereof. In one or moreembodiments, one or more surfaces of the valve prosthesis and/or one ormore of its components or portions may comprise, be covered with, becoated with, or be attached or coupled to one or more glues and/oradhesives, such as a bioglue or bioadhesive used to help anchor and/orseal the valve prosthesis to native tissue.

In one or more embodiments, one or more surfaces of the valve prosthesisand/or one or more of its components or portions may comprise, becovered with, be coated with, or be attached or coupled to one or moreradioactive materials and/or biological agents, for example, ananticoagulant agent, an antithrombotic agent, a clotting agent, aplatelet agent, an anti-inflammatory agent, an antibody, an antigen, animmunoglobulin, a defense agent, an enzyme, a hormone, a growth factor,a neurotransmitter, a cytokine, a blood agent, a regulatory agent, atransport agent, a fibrous agent, a protein, a peptide, a proteoglycan,a toxin, an antibiotic agent, an antibacterial agent, an antimicrobialagent, a bacterial agent or component, hyaluronic acid, apolysaccharide, a carbohydrate, a fatty acid, a catalyst, a drug, avitamin, a DNA segment, a RNA segment, a nucleic acid, a lectin, anantiviral agent, a viral agent or component, a genetic agent, a ligandand/or a dye (which acts as a biological ligand). Biological agents maybe found in nature (naturally occurring) or may be chemicallysynthesized by a variety of methods well known in the art.

In one or more embodiments, valve prosthesis and/or one or more of itscomponents or portions may comprise, be coated with, be covered with, orbe attached or coupled to one or more biological cells or tissues, forexample, tissue cells, cardiac cells, contractile cells, muscle cells,heart muscle cells, smooth muscle cells, skeletal muscle cells,autologous cells, allogenic cells, xenogenic cells, stem cells,genetically engineered cells, non-engineered cells, mixtures of cells,precursor cells, immunologically neutral cells, differentiated cells,undifferentiated cells, natural tissue, synthetic tissue, animal tissue,human tissue, porcine tissue, equine tissue, porcine tissue, bovinetissue, ovine tissue, autologous tissue, allogenic tissue, xenogenictissue, autograft tissue, genetically engineered tissue, non-engineeredtissue, mixtures of tissues, cardiac tissue, pericardial tissue, cardiacvalve tissue, membranous tissue, and/or intestinal submucosa tissue. Inone or more embodiments, valve prosthesis and/or one or more of itscomponents or portions may comprise, be covered with, be coated with, orbe attached or coupled to one or more materials that promote the growthof cells and/or tissue. In one or more embodiments, the cell and/ortissue promoting materials may comprise, possess or be configured topossess physical characteristics such as size, shape, porosity, matrixstructure, fiber structure, and/or chemical characteristics such asgrowth factors, biological agents, that promote and/or aid, for example,in the adherence, proliferation and/or growth of desired cells and/ortissues in vivo following implantation or ex vivo prior to implantation.In one or more embodiments, the cell and/or tissue promoting materialsmay accelerate the healing response of the patient following theimplantation of the valve prosthesis. In one or more embodiments, thecell and/or tissue promoting materials may comprise pockets, parachutes,voids, and/or openings, for example, that may trap cells and/or tissuesand/or promote cells and/or tissues to proliferate, grow and/or heal.

In one or more embodiments, the valve prosthesis may comprise one ormore active and/or passive fixation elements or members such as anchors,barbs, prongs, clips, grommets, sutures, and/or screws. In one or moreembodiments, one or more active and/or passive fixation elements ormembers may be delivered separately from the valve prosthesis. In one ormore embodiments, one or more active and/or passive fixation elements ormembers may be delivered during the valve prosthesis implant procedure.In one or more embodiments, one or more active and/or passive fixationelements or members may be delivered after the valve prosthesis implantprocedure. In one or more embodiments, one or more active and/or passivefixation elements or members may be delivered using the valve prosthesisdelivery system. In one or more embodiments, one or more active fixationelements or members may be activated by pushing, pulling, twisting,screwing and/or turning motion or movement. In one or more embodiments,one or more fixation elements or members may be released or engaged viaan unsheathing, an unsleeving, a dissolving, and/or a degrading action.In one or more embodiments, one or more active and/or passive fixationelements or members may be delivered using a fixation element deliverysystem. In one or more embodiments, one or more active and/or passivefixation elements or members may be coupled, connected, and/or attachedto the valve prosthesis stent or frame. In one or more embodiments, thevalve prosthesis stent or frame may comprise a unitary structure thatcomprises one or more active and/or passive fixation elements. In one ormore embodiments, one or more active and/or passive fixation elementsmay be coupled, connected, and/or attached to the valve prosthesis skirtand/or graft material. In one or more embodiments, one or more fixationelements or members may be designed to increasingly engage one or moreheart tissues and/or structures via any movement of the valve prosthesisrelative to heart tissue and/or structures during one or more cardiaccycles. For example, a barbed fixation element that further embedsitself into tissue via movement of the valve prosthesis relative totissue in one direction and then resists movement of the valveprosthesis relative to tissue in the opposite direction.

In one or more embodiments, the valve prosthesis 20 may comprise one ormore posts or tabs 29 circumferentially spaced about a circumferencedefined by the stent frame 22. The posts or tabs 29 can assume variousforms, and in some embodiments are identical. One or more posts or tabs29 may comprise one or more slots or openings. The posts or tabs 29 canbe used to couple or retain the valve prosthesis 20 to a valvedeployment or delivery system 10.

In certain embodiments, the valve prosthesis 20 is configured forrepairing an aortic valve. Alternatively, other shapes are alsoenvisioned to adapt to the specific anatomy of the valve to be repaired(e.g., stented prosthetic heart valves in accordance with the presentdisclosure can be shaped and/or sized for replacing a native aortic,mitral, pulmonic and/or tricuspid valve).

The prosthetic heart valve 20 described herein may be implanted into anannulus of a native cardiac valve via a suitable delivery route orprocedure. For example, the valve prosthesis 20 may be delivered throughan artery or vein, a femoral artery, a femoral vein, a jugular vein, asubclavian artery, an axillary artery, an aorta, an atrium, and/or aventricle. The valve prosthesis 20 may be delivered via a transfemoral,transapical, transseptal, transatrial, transventrical, or transaorticprocedure.

In some embodiments, an aortic valve prosthesis 20 may be deliveredtransfemorally. In such a delivery, a delivery device 10 and the valveprosthesis 20 can be advanced in a retrograde manner through the femoralartery and into the patient's descending aorta. The delivery device 10and valve prosthesis 20 can then be advanced under fluoroscopic guidanceover the aortic arch, through the ascending aorta, and mid-way acrossthe defective aortic valve. Once positioning of the catheter isconfirmed, the delivery device 10 can deploy the valve prosthesis 20within the defective valve in a stepped deployment procedure. The valveprosthesis 20 can then expand against and align the prosthesis withinthe defective valve.

In some embodiments, a mitral valve prosthesis 20 may be deliveredtransfemorally. In such a delivery, a delivery device 10 and the valveprosthesis 20 can be advanced in a retrograde manner through the femoralartery and into the patient's descending aorta. The delivery device 10and valve prosthesis 20 can then be advanced under fluoroscopic guidanceover the aortic arch, through the ascending aorta, into the leftventricle, and mid-way across the defective mitral valve. Oncepositioning of the catheter is confirmed, the delivery device 10 candeploy the valve prosthesis 20 within the defective valve in a steppeddeployment procedure. The valve prosthesis 20 can then expand againstand align the prosthesis within the defective valve.

In some embodiments, a valve prosthesis 20 can be delivered via atransapical procedure. In a transapical procedure, a delivery device 10and the valve prosthesis 20 can be inserted into a patient's leftventricle through an incision created in the apex of the patient'sheart. A dilator may be used to aid in the insertion of the deliverydevice 10 and the valve prosthesis 20. In this approach, the nativevalve (for example, a mitral valve or an aortic valve) may be approachedfrom either a downstream direction relative to the blood flow for amitral valve or an upstream direction relative to the blood flow for anaortic valve. The delivery device 10 and valve prosthesis 20 may beadvanced mid-way across the defective valve. Once positioning of thecatheter is confirmed, the delivery device 10 can deploy the valveprosthesis 20 within the defective valve in a stepped deploymentprocedure. The valve prosthesis 20 can then expand against and align theprosthesis within the defective valve.

In some embodiments, a mitral valve prosthesis 20 can be delivered via atransatrial procedure. In such a procedure, a delivery device 10 and thevalve prosthesis 20 can be inserted through an incision made in the wallof the left atrium of the patient's heart. The delivery device 10 andvalve prosthesis 20 may be advanced mid-way across the defective mitralvalve. Once positioning of the catheter is confirmed, the deliverydevice 10 can deploy the valve prosthesis 20 within the defective valvein a stepped deployment procedure. The valve prosthesis 20 can thenexpand against and align the prosthesis within the defective valve.

In some embodiments, an aortic valve prosthesis 20 can be delivered viaa transatrial procedure. In such a procedure, a delivery device 10 andthe valve prosthesis 20 can be inserted through an incision made in thewall of the left atrium of the patient's heart. The delivery device 10and the valve prosthesis 20 may be advanced through the left atrium,through the mitral valve, into the left ventricle, and mid-way acrossthe defective aortic valve. Once positioning of the catheter isconfirmed, the delivery device 10 can deploy the valve prosthesis 20within the defective valve in a stepped deployment procedure. The valveprosthesis 20 can then expand against and align the prosthesis withinthe defective valve.

In one or more embodiments of the present invention, valve prosthesis 20and/or one or more of its components or portions may be delivered, forexample, through a thoracotomy, a sternotomy, percutaneously,transvenously, arthroscopically, endoscopically, for example, through apercutaneous port, a stab wound or puncture, through a small incision,for example, in the chest, groin, abdomen, neck, leg, arm, or incombinations thereof. In one or more embodiments of the presentinvention, valve prosthesis 20 and/or one or more of its components orportions may be delivered, for example, via a transvascular method, atransarterial method, a transvenous method, a transcardiac method, atransatrial method, a transventrical method, transapical method, atransseptal method, a transaortic method, a transcatheter method, asurgical method, a beating heart method, a stopped heart method, apump-assisted method, and/or a cardiopulmonary bypass method.

In one or more embodiments of the present invention, valve prosthesis 20and/or one or more of its components or portions may be positioned in,positioned through, and/or positioned adjacent to, for example, anatural valve, a native valve, a synthetic valve, a replacement valve, atissue valve, a mechanical valve, a mitral valve, an aortic valve, apulmonary valve, a tricuspid valve, a valve component, a valve annulus,a valve leaflet, chordea, and/or a valve commissure.

The sealing mechanism 30 is positioned over at least a portion of theouter surface of the stent frame 22 of the prosthetic heart valve 20. Insome embodiments, the sealing mechanism 30 on the prosthetic heart valve20 may be referred to as a skirt. In other embodiments, the sealingmechanism 30 extends over a portion of an inner surface of the stentframe 22 of the prosthetic heart valve 20.

At least a portion of the sealing mechanism 30 is fabricated from asemi-permeable membrane 32 that is used in conjunction with an osmoticgradient driving material 34, as illustrated in FIG. 3. The sealingmechanism 30 may be fabricated from multiple semi-membrane layers 32 asis discussed in more detail herein.

The semi-permeable membrane 32 used in conjunction with the sealingmechanism 30 may be fabricated from a variety of materials. One type ofsemi-permeable membrane 32 that is suitable for use in conjunction withthe sealing mechanism 30 is a cellulosic membrane.

The cellulose membrane can be fabricated from natural materials,synthetic materials or a combination of natural materials and syntheticmaterials. In certain embodiments, at least one of an inner surface andan outer surface of the cellulose membrane can be modified. Examples oftwo suitable cellulosic membranes are cellulose ester or regeneratedcellulose.

The semi-permeable membrane 32 can be formed with a pore size andselectivity based upon the osmotic gradient driving material that isused. In certain embodiments, the molecular cutoff range of thesemi-permeable membrane 32 is between about 1 and 1,000,000 kilodaltons.

One or more portions of the semi-permeable membrane 32 may be coatedwith one or more materials as previously described. In certainembodiments, one or more portions of the semi-permeable membrane 32 maybe coated with at least one protein and/or at least one biodegradablepolymer coating layer 36. In certain embodiments, the coating layer 36may prevent or substantially reduce diffusion of fluid through one ormore portions of the semi-permeable membrane 32 when the prostheticheart valve 20 is stored in a fluid solution such as an aqueous solutionprior to use.

In certain embodiments, the coating layer 36 may be dissolvable uponexposure to a blood environment. For example, the coating layer 36 mayrapidly dissolve and/or disintegrate upon introduction into a bloodenvironment. The dissolvable nature of the coating layer 36 permitsdiffusion of fluid through the semi-permeable membrane 32 once theprosthetic heart valve 20 is in the blood environment to therebyfacilitate swelling of the sealing mechanism 30.

In another embodiment, the semi-permeable membrane 32 may be coated witha coating layer 36 that is soluble in a solvent so that the coatinglayer 36 will dissolve and/or disintegrate upon contact with theparticular solvent such as alcohol. When the prosthetic heart valve 20is stored in an aqueous solution prior to use, the coating layer 36restricts or prevents diffusion of fluid through the semi-permeablemembrane 32 and thus prevents the swelling of the sealing mechanism 30.

In certain embodiments, prior to loading the prosthetic heart valve 20onto the delivery system, the prosthetic heart valve 20 is brieflyexposed to a solvent such as by submersion in the solvent. This exposurein a solvent causes the coating layer 36 to dissolve. Thereafter, theprosthetic heart valve 20 is implanted and the osmotic gradient drivingmaterial 34 promotes diffusion of fluid through the semi-permeablemembrane 32 to thereby cause osmotic swelling of the sealing mechanism30.

The osmotic gradient driving material 34 is associated with the sealingmechanism 30. In certain embodiments, the osmotic gradient drivingmaterial is placed in an interior of the sealing mechanism 30. Forexample, the osmotic gradient driving material 34 may be placed betweensemi-permeable membrane layers 32 used in fabricating the sealingmechanism 30. In another embodiment, the osmotic gradient drivingmaterial 34 is incorporated in one or more materials that are used tofabricate sealing mechanism 30 such as one or more portions of thesemi-permeable membrane 32.

A variety of materials may be utilized to drive an osmotic gradient inthe sealing mechanism 30. In certain embodiments, the osmotic gradientdriving materials are organic and/or inorganic compounds that are eitherpositively or negatively charged. Examples of suitable organic compoundsinclude polysaccharides such as glycosaminoglycans. The organiccompounds can also be proteins. Examples of suitable proteins includenatural or synthetic peptides containing charged amino acid residues.

Examples of suitable inorganic compounds include synthetic particlessuch as polyionic microbeads or nanoparticles. Other suitable inorganiccompounds include sodium chloride or other salts that are conventionallyfound in physiological blood. In still other embodiments, gradientdriving material 34 may comprise a combination of at least one inorganiccompound such as a salt and at least one organic compound such as acharged organic compound.

The osmotic gradient driving material 34 is provided at an effectiveconcentration. As used herein, the term effective concentration meansthat the osmotic gradient driving material causes a sufficient amount offluid such as water to be drawn into the sealing mechanism 30 to providea desired amount of swelling of the sealing mechanism 30.

The effective concentration thereby varies depending on the osmoticgradient driving material that is used in conjunction with the sealingmechanism 30. Even though a precise concentration range for the osmoticgradient driving material is not provided, it is within the expertise ofa person of skill in the art to determine the suitable concentrationrange for a particular osmotic gradient driving material. The materialused in fabricating the semi-permeable membrane 32 may also affect theswelling of the sealing mechanism 30. Such a determination would notinvolve undue experimentation.

The semi-permeable membrane 32 in the sealing mechanism 30 may take avariety of forms. In one configuration, there are two semi-permeablemembrane layers 32 and an interstitial space therebetween. In anotherconfiguration, there are three semi-permeable membrane layers 32 withtwo interstitial spaces therebetween.

In certain embodiments, different materials may be placed in the twointerstitial spaces. An advantage of this configuration is that itallows for swelling in the inner space as well as protein/drug diffusionfrom the outer semi-permeable membrane. In yet another configuration,there are greater than three semi-permeable membrane layers 32.

The osmotic gradient driving material 34 is placed in at least one ofthe interstitial spaces. The form of the materials that are used in theosmotic gradient driving material would impact the manner in which theosmotic gradient driving material is placed in the interstitial space.

For example, if the osmotic gradient driving material 34 is provided ina particulate form, the osmotic gradient driving material 34 may besprinkled on one of the semi-permeable membranes 32 as an initial stepin forming the sealing mechanism 30.

In other embodiments, the osmotic gradient driving material 34 may beformed into a layer that is placed between semi-permeable membranelayers 32 during the process of fabricating the sealing mechanism 30.

One or more thicknesses of one or more portions of the sealing mechanism30 may be selected based upon a variety of factors. An example of onesuch factor is the irregularity of the native valve where it is desiredto implant the prosthetic heart valve 20. Another factor in selectingthe thickness of the sealing mechanism 30 is the inner diameter of thedelivery system 10 in which the prosthetic heart valve 20 and associatedsealing mechanism 30 must be compressed prior to deployment.

A factor in the thickness of the sealing mechanism 30 is thecompressibility of the semi-permeable membrane 32. Additionally, formingthe sealing mechanism 30 too thin may also negatively impact thestrength of the sealing mechanism 30 and thereby increase the potentialthat the sealing mechanism 30 is damaged during the process ofdelivering the prosthetic heart valve 20.

In certain embodiments, the sealing mechanism 30 has a thickness of upto about 0.1 millimeters. In other embodiments, the sealing mechanism 30has a thickness of between about 50 and 200 microns. In membraneconfigurations that utilize two layers, the double membrane thicknesscould be between about 100 and 300 microns with the additional thicknessto accommodate one or more osmotic gradient driving materials such asone or more salts used in the sealing mechanism 30.

Imaging analysis of current prosthetic heart valve devices has showngaps of up to about 5 millimeters between an outer surface of the stentframe and an inner lining of an aortic root. Because of the shape of theaortic root, this gap may not be consistent around the stent frame 22but this gap may be particularly evident in regions of nativecommissure.

Therefore, the sealing mechanism 30 should be constructed to allowradial expansion or swelling of up to about 5 millimeters when placed ina blood environment as well as to permit passive diffusion of fluid suchas plasma through the semi-permeable membrane 32 structure.

The sealing mechanism 30 should be formed with a swelling size that issufficiently large so that the swelling of the sealing mechanism 30 uponexposure to blood is sufficiently large to fill any gaps between theprosthetic heart valve 20 and the native tissue. On the other hand, theswelling should not be too great as to put undue pressure on the nativetissue and/or prosthetic heart valve 20 to cause collapse of the stentframe 22 and/or prevent full expansion of the stent frame 22 becausesuch actions could impede the operation of the valve structure 24.

The sealing mechanism 30 may be fabricated with different dimensions.For example, increasing the width may provide the sealing mechanism 30with an enhanced ability to form a seal between the prosthetic heartvalve 20 and the native tissue. However, increasing the width of thesealing mechanism 30 may decrease flexibility of the sealing mechanism30 such as when the prosthetic heart valve 20 is being delivered to thelocation where it is intended to be deployed.

In certain embodiments, the sealing mechanism 30 may be attached to thestent frame 22 to restrict movement of the sealing mechanism 30 withrespect to the stent frame 22. A variety of techniques may be used toattach the sealing mechanism 30 to the stent frame 22. Attachment of thesealing mechanism 30 to the stent frame 22 is particularly importantwhen the stent frame 22 is in the collapsed configuration as well aswhen the stent frame 22 is moving between the collapsed and expandedconfigurations.

In certain embodiments, one or more mechanical fasteners such as atleast one suture may be used to secure the sealing mechanism 30 in adesired position with respect to the stent frame 22. The number ofsutures utilized depends on factors such as the width of the sealingmechanism 30.

Another technique that can be used to attach the sealing mechanism 30 tothe stent frame 22 is the use of one or more adhesives. A person ofskill in the art would appreciate that there are a variety ofbiocompatible adhesives. One or more biocompatible adhesives may be usedalone or in conjunction with one or more mechanical fasteners. Yetanother technique that can be used to attach the sealing mechanism 30 tothe stent frame 22 is melting and/or welding such as with direct heat orultrasound.

Another configuration for attaching the sealing mechanism 30 to thestent frame 22 involves placing layers 32 a over at least a portion ofthe inner and outer surfaces of the stent frame 22 and then sealingthese layers 32 a together to thereby retain the stent frame 22 betweenthe layers 32 a, as illustrated in FIG. 4. In certain embodiments, thelayers 32 a are placed on opposite surfaces of the stent frame 22. Incertain embodiments, one or more layers 32 a may be fabricated from oneor more semi-permeable membranes. In certain embodiments, at least oneadditional semi-permeable membrane layer 32 is attached to the layer 32a on the outer surface of the stent frame 22. In certain embodiments, anosmotic gradient material 34 is placed between the semi-permeable layer32 and the outer layer 32 a. In certain embodiments, semi-permeablemembrane 32 may comprise a coating layer 36.

In certain embodiments, the sealing mechanism 30 may have a generallyflat configuration and is wrapped around the outer surface of theprosthetic heart valve 20. Depending upon factors such as the thicknessof the sealing mechanism 30, the sealing mechanism 30 may be wrappedaround the outer surface of the prosthetic heart valve 20 more than onetime.

In another embodiment, the sealing mechanism 30 may have a tubularconfiguration. When the sealing mechanism 30 has a tubularconfiguration, the sealing mechanism 30 is positioned over a portion ofthe outer surface of the prosthetic heart valve 20. The stent frame 22may be moved to the collapsed configuration to facilitate placing thetubular sealing mechanism 30 thereon.

In one or more embodiments, the valve prosthesis 20 may be delivered viaa delivery system 10 that comprises a catheter with a retractablecompression sleeve, sheath, or capsule 32 that covers the valveprosthesis 20, as illustrated in FIG. 5, until it is to be deployed, atwhich point the sheath 32 may be retracted to allow the stent frame 22to self-expand.

Once the prosthetic heart valve 20 is in a desired implant position,sheath 32 is retracted and the prosthetic heart valve 20 is allowed touncompress or expand, as illustrated in FIG. 6. After implantation, adifference in salt concentration between the sealing mechanism 30 andthe blood environment adjacent thereto will produce an osmotic imbalanceand such osmotic imbalance will cause water in the blood to be drawninto the sealing mechanism 30. As the water is drawn into the sealingmechanism 30, the sealing mechanism 30 swells, which enhances thecontact between the prosthetic heart valve 20 and the native valve,which reduces the potential of paravalvular leakage.

Force caused by swelling of the sealing mechanism 30 should be primarilydirected outwards from the prosthetic heart valve 20 as inward forcecaused by the swelling of the sealing mechanism 30 could producenegative effects on the operation of the valve structure 24 such asimpeding movement of the valve structure 24 between open and closedconfigurations.

For example, the swelling of the sealing mechanism 30 should not besufficiently great so that the sealing mechanism 30 causes the stentframe 22 to collapse or otherwise deform in a manner that reduces theengagement between the prosthetic heart valve 20 and the native valve.

Additionally, the swelling of the sealing mechanism 30 should not causemigration of the prosthetic heart valve 20 with respect to the nativevalve. Both of the preceding phenomena could impact the success of theprocedure that is performed using the prosthetic heart valve 20according to this invention.

A variety of tests can be used to detect valve migration and/or valveframe deformation. Examples of these tests include a hydrodynamics test(pulse duplicator), which detects significant deformation of theprosthetic heart valve due to swelling of the semi-permeable membrane. Amigration test can be used to detect prosthetic heart valve migrationwith respect to native tissue such as the aortic root. A radiopaqueleakage test can be used to detect the presence of paravalvular leakage.

In operation, in one embodiment of utilizing the prosthetic heart valvedeployment system 10, the components are loaded into a compressedarrangement illustrated in FIG. 5. The sealing mechanism 30 does notneed to be in a stationary position with respect to the stent frame 22.In an alternative embodiment, the sealing mechanism 30 can be separatefrom the stent frame 22 such as distal to the stent frame 22. Thesealing mechanism 30 may be pulled over the stent frame 22 duringdeployment such as using sutures or alternative mulling mechanisms.

A compression sleeve, sheath, or capsule 32 at least partially coversthe valve prosthesis 20 and thereby secures the valve prosthesis 20 tothe valve deployment system 10. In one embodiment, after appropriatepreparation of the patient, the distal end of the prosthetic heart valvedeployment system 10 is advanced through the patient's vascular systemand advanced across a native valve 92 such as the native aortic valve.

In one embodiment, the capsule 32 is maintained in a substantiallystationary position as the prosthetic heart valve 20 is advanceddistally into the left ventricle. In another embodiment, the capsule 32and the prosthetic heart valve 20 are advanced into the left ventricle.The prosthetic heart valve 20 is maintained in a substantiallystationary position as the capsule 32 is proximally retracted.

In both of the preceding configurations, the prosthetic heart valve 20expands from the compressed arrangement to the expanded arrangement asthe capsule 32 moves off the prosthetic heart valve 20, as illustratedin FIG. 6. The prosthetic heart valve 20 is then released from thedeployment system, as illustrated in FIG. 7, and the deployment system10 is removed from the patient to complete the procedure.

Movement of the capsule 32 off of the prosthetic heart valve 20 alsocauses the sealing mechanism 30 to come into contact with blood flowingthrough the cardiovascular system in which the prosthetic heart valve 20has been implanted. The osmotic gradient driving material 34 causesfluid such as water to be drawn through the semi-permeable membrane 32,which causes the sealing mechanism 30 to swell. As illustrated in FIG.7, such swelling of the sealing mechanism 30 enhances a seal between theprosthetic heart valve 20 and the native valve 92, which reduces thepotential of blood leaking between the prosthetic heart valve 20 and thenative valve 92.

While the concepts disclosed herein are described for use in conjunctionwith prosthetic heart valves, it is possible for the semi-permeablemembrane leakage prevention system to be used in other applications.Examples of such other leakage systems include other components that areimplanted and/or inserted into a living body where it is desired toprevent blood or other fluid from leaking by passing around theimplanted or inserted component.

While various embodiments have been described above, it should beunderstood that they have been presented only as illustrations andexamples of the present invention, and not by way of limitation. It willbe apparent to persons skilled in the relevant art that various changesin form and detail can be made therein without departing from the spiritand scope of the invention. Thus, the breadth and scope of the presentinvention should not be limited by any of the above-described exemplaryembodiments, but should be defined only in accordance with the appendedclaims and their equivalents. It will also be understood that eachfeature of each embodiment discussed herein, and of each reference citedherein, can be used in combination with the features of any otherembodiment. All patents and publications discussed herein areincorporated by reference herein in their entirety.

What is claimed is:
 1. A method of reducing paravalvular leakage from aprosthetic heart valve, wherein the method comprises: providing aprosthetic heart valve comprising a stent frame having a surface, avalve structure associated with the stent frame, a sealing mechanismincluding at least one semi-permeable membrane and an osmotic gradientdriving material, wherein the sealing mechanism is positioned at leastpartially over the surface of the stent frame, wherein the prostheticheart valve further includes a dissolvable coating layer on the at leastone semi-permeable membrane; deploying the prosthetic heart valve in apatient, wherein the osmotic gradient driving material causes fluid ofthe patient to pass through the at least one semi-permeable membrane,wherein the fluid that passes through the at least one semi-permeablemembrane causes the sealing mechanism to swell and such swelling reducesparavalvular leakage between the prosthetic heart valve and tissue ofthe patient; exposing the dissolvable coating layer to at least one ofblood and a solvent; and dissolving the dissolvable coating layer. 2.The method of claim 1, and further comprising sealing the osmoticgradient driving material within the at least one semi-permeablemembrane.
 3. The method of claim 1, wherein the at least onesemi-permeable membrane comprises two semi-permeable membranes andwherein the osmotic gradient driving material is placed between the twosemi-permeable membranes.
 4. The method of claim 1, wherein the osmoticgradient driving material comprises at least one organic or inorganiccompound that is positively or negatively charged.
 5. The method ofclaim 1, wherein the osmotic gradient driving material comprises atleast one inorganic salt and at least one charged organic compound. 6.The method of claim 1, wherein the at least one semi-permeable membraneis fabricated from a cellulosic material.
 7. The method of claim 1, andfurther comprising securing the sealing mechanism to the stent frame byat least one of a mechanical fastener and a biocompatible adhesive. 8.The method of claim 1, wherein the stent frame is expandable from acompressed configuration to an expanded configuration and wherein thevalve structure comprises at least two leaflets.
 9. The method of claim1, wherein the step of exposing the dissolvable coating layer to atleast one of blood and a solvent includes exposing the dissolvablecoating layer to blood and a solvent.
 10. The method of claim 1, whereinthe two semi-permeable membranes include an inner membrane and an outermembrane, and the osmotic gradient driving material is placed betweenthe inner and outer membranes, further wherein the stent frame ispositioned between the inner membrane and the outer membrane.
 11. Amethod of reducing paravalvular leakage from a prosthetic heart valve,wherein the method comprises: providing a prosthetic heart valveincluding a stent frame having: a surface, a valve structure associatedwith the stent frame, and a sealing mechanism, wherein the sealingmechanism includes: two semi-permeable membranes including an innermembrane and an outer membrane, and at least one osmotic gradientdriving material placed between the inner and outer membranes, furtherwherein the stent frame is positioned between the inner membrane and theouter membrane; and deploying the prosthetic heart valve in a patient,wherein the osmotic gradient driving material causes fluid of thepatient to pass through the two semi-permeable membranes, wherein thefluid that passes through the two semi-permeable membranes causes thesealing mechanism to swell and such swelling reduces paravalvularleakage between the prosthetic heart valve and tissue of the patient.12. The method of claim 11, wherein each of the inner and outermembranes are made of materials having a molecular cutoff range between1 and 1,000,000 kilodaltons.
 13. The method of claim 11, wherein theprosthetic heart valve further includes a dissolvable coating layer onthe outer membrane.
 14. The method of claim 13, wherein the methodfurther includes: exposing the dissolvable coating layer to blood; anddissolving the dissolvable coating layer.
 15. The method of claim 13,wherein the method further includes: exposing the dissolvable coatinglayer to a solvent; and dissolving the dissolvable coating layer.